Understanding Storm Track Position and Intensity Across a Range of Timescales

了解不同时间尺度内的风暴轨迹位置和强度

• 批准号: 1742944
• 负责人: Tiffany Shaw
• 金额: $ 45.04万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-01 至 2022-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1742944&HistoricalAwards=false
• 关键词: Understanding; Storm; Track; Position; Intensity

Warm days preceding and cold days following the passage of frontal weather systems are a familiar feature of winter weather in the continental US and other middle latitude regions. This alternation is important not only for local weather but for the global transport of heat and moisture, as warm moist air crosses the middle latitudes from the tropics to the poles while colder and drier transits in the opposite direction. This north-south exchange of heat and moisture plays an essential role in earth's climate, keeping the poles from getting too cold while limiting the temperature excess of the tropics. Such climatic effects of weather systems are commonly studied by looking at the midlatitude stormtracks, defined as zones of maximum weather system activity. In the Northern Hemisphere separate stormtracks are centered over the northern North Pacific and North Atlantic, while in the Southern Hemisphere a continuous stormtrack extends around the "roaring 40s" over the uninterrupted Southern Ocean.This project seeks to understand how the mean latitude of the stormtracks, and the and strength of the energy transport by the weather systems moving along them, change in response to external factors including the seasonal cycle of solar heating, greenhouse gas concentrations, stratospheric aerosols, ice age cycles, and the distribution of continents and oceans. The research is conducted using a theoretical framework developed by the Principal Investigator (PI) in which stormtracks are characterized in terms of the flux of moist static energy (MSE) across them, where MSE is a measure of energy which includes the thermal energy associated with air temperature, the latent energy of water vapor released as heat during condensation, and the potential energy of air parcels lifted against the force of gravity. The MSE flux in stormtracks works in concert with MSE flux in circulations around large stationary pressure centers such as the Aleutian Low and the Bermuda High (referred to as stationary waves), and the circumglobal meridional overturning circulations (the Hadley and Ferrel cells), to transport energy from the tropics to the poles and balance the atmospheric energy budget. Much of the previous research on stormtracks has been conducted through analysis of the momentum budget and related quantities (potential vorticity and Eliassen-Palm flux, for instance), thus the MSE analysis of the present work offers a novel and complementary perspective.Preliminary work by the PI and colleagues shows compensation between MSE flux in stormtracks and stationary waves as a prominent feature of the seasonal cycle and the midlatitude response to El Nino events, while compensation between MSE flux in stormtracks and meridional overturning circulations appears in simulations of the atmopsheric response to greenhouse gases and the radiative effects of aerosols. The present work extends these investigations and seeks to determine the fundamental dynamics through which these compensations, in which changes in stormtrack MSE flux are accompanied by opposing changes in other forms of MSE flux, come about. The work is conducted through a combination of observational analysis and simulations with numerical models at varying levels of complexity.The work has societal relevance as well as scientific interest due to the importance of stormtrack behavior for human activities in the midlatitudes, including the continental US. In addition, one goal of the research is the identification of "emergent constraints" which can be used to assess the credibility of climate change simulations. Emergent constraints are relationships that emerge between model-to-model variations in simulated present-day climate (the predictor) and model-to-model differences in simulated future climate change (the predictand). Such constraints are used to assess the credibility of climate change projections, as models which incorrectly represent the predictor, which can be compared to real-world observations, are likely to produce comparable misrepresentations in their simulations of future climate change. Such tests of climate change projections are valuable given the use of climate models to inform climate change adaptation efforts. The project also supports a graduate student and the participation of an undergraduate, thereby providing for the education and training of the future workforce in this research area.

锋面天气系统通过之前的温暖日子和之后的寒冷日子是美国大陆和其他中纬度地区冬季天气的常见特征。 这种交替不仅对当地天气很重要，而且对全球热量和水分的输送也很重要，因为暖湿空气从热带穿越中纬度地区到达两极，而更冷和更干燥的空气则从相反的方向过境。 这种南北之间的热量和水分交换在地球气候中起着至关重要的作用，使两极地区不会变得太冷，同时限制了热带地区的温度过高。 天气系统的这种气候影响通常通过观察中纬度风暴轨迹来研究，中纬度风暴轨迹被定义为最大天气系统活动的区域。 在北方半球，单独的风暴路径集中在北太平洋北部和北大西洋，而在南半球，一个连续的风暴路径在“咆哮的40年代”在不间断的南大洋上延伸。本项目试图了解风暴路径的平均纬度，以及沿着它们移动的天气系统的能量输送的强度，气候变化是对外部因素的反应，包括太阳加热的季节性周期、温室气体浓度、平流层气溶胶、冰河时代周期以及大陆和海洋的分布。 这项研究是使用由首席研究员（PI）开发的理论框架进行的，其中风暴轨迹的特征在于它们之间的湿静态能量（MSE）通量，其中MSE是能量的量度，包括与空气温度相关的热能，凝结过程中释放的水蒸气的潜热，以及克服重力而上升的气团的势能。 风暴道中的MSE通量与阿留申低压和百慕大高压（称为驻波）等大型静止气压中心周围的环流中的MSE通量以及环全球纬向翻转环流（哈德利环流和费雷尔环流）协同工作，将能量从热带输送到两极，平衡大气能量收支。 以前对风暴轨迹的研究大多是通过分析动量收支和相关量来进行的（例如，位涡和Eliassen-Palm通量），因此，当前工作的MSE分析提供了一个新的和补充的视角。PI和同事们的初步工作表明，风暴路径中的MSE通量与定常波之间的补偿是季节循环和中纬度的一个突出特征在模拟大气对温室气体和气溶胶辐射效应的响应时，风暴路径中的MSE通量与纬向翻转环流之间存在补偿。 目前的工作扩展了这些调查，并试图确定这些补偿，其中在stormtrack MSE通量的变化是伴随着其他形式的MSE通量的相对变化，通过这些基本的动态。 这项工作是通过观测分析和模拟与数值模式在不同程度的复杂性相结合进行的。由于风暴轨迹行为对中纬度地区（包括美国大陆）人类活动的重要性，这项工作具有社会相关性和科学兴趣。 此外，研究的一个目标是确定“紧急约束”，可用于评估气候变化模拟的可信度。涌现约束是在模拟的当前气候的模式间变化（预测因子）和模拟的未来气候变化的模式间差异（预测因子）之间出现的关系。这些制约因素被用来评估气候变化预测的可信度，因为模型如果不正确地表示预测值，而预测值可以与现实世界的观测值进行比较，那么在对未来气候变化的模拟中可能会产生类似的错误表述。 鉴于气候模型可用于为适应气候变化的努力提供信息，这种气候变化预测测试是很有价值的。该项目还支持一名研究生和一名本科生的参与，从而为该研究领域未来的劳动力提供教育和培训。

项目成果

Atmospheric Diffusivity: A New Energetic Framework for Understanding the Midlatitude Circulation Response to Climate Change

大气扩散率：了解中纬度环流对气候变化响应的新能量框架

• DOI: 10.1029/2019jd031206
• 发表时间: 2020
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: Mooring, Todd A.;Shaw, Tiffany A.
• 通讯作者: Shaw, Tiffany A.

The Midlatitude Response to Polar Sea Ice Loss: Idealized Slab-Ocean Aquaplanet Experiments with Thermodynamic Sea Ice

中纬度地区对极地海冰损失的响应：热力学海冰的理想化板状海洋水行星实验

• DOI: 10.1175/jcli-d-21-0508.1
• 发表时间: 2022
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Shaw, Tiffany A.;Smith, Zoë
• 通讯作者: Smith, Zoë

Hydrological Cycle Changes Explain Weak Snowball Earth Storm Track Despite Increased Surface Baroclinicity

尽管表面斜压增加，水文循环变化解释了雪球地球风暴路径的弱化

• DOI: 10.1029/2020gl089866
• 发表时间: 2020
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Shaw, Tiffany A.;Graham, R. J.
• 通讯作者: Graham, R. J.

Surface Fluxes Modulate the Seasonality of Zonal-Mean Storm Tracks

• DOI: 10.1175/jas-d-19-0139.1
• 发表时间: 2020-02-01
• 期刊: JOURNAL OF THE ATMOSPHERIC SCIENCES
• 影响因子: 3.1
• 作者: Barpanda, Pragallva;Shaw, Tiffany A.
• 通讯作者: Shaw, Tiffany A.

Mechanisms of Future Predicted Changes in the Zonal Mean Mid-Latitude Circulation

未来预测纬向平均中纬度环流变化的机制

• DOI: 10.1007/s40641-019-00145-8
• 发表时间: 2019
• 期刊: Current Climate Change Reports
• 影响因子: 9.5
• 作者: Shaw, Tiffany A.